This research investigates aspects of information processing in pigeons. The following question is asked: Why do pigeons require prolonged inspection times (several seconds) of a stimulus sample to perform at a high level in a matching-to-sample task? Possible explanations include a preparation time explanation, one based on trace decay notion, one based on possible rehearsal mechanisms, and finally a multiple-look hypothesis. Proposed research also examines the following questions: Why do two-element samples require about twice as much inspection time as one-element samples for adequate performance? Is this a function of the particular stimuli used? Will it be found in integral stimuli as opposed to separable stimuli? What effect does cue separation have on this phenomenon? Is the effect a product of the particular procedure or can analogous effects be found with reaction-time measurements? Selective-attention instructions facilitate performance on the relevant dimension and cause deterioration on the irrelevant dimension. Where in the information processing sequence does this occur? Processing of natural stimuli (such as grain and photographs of grains) will be examined to determine whether information processing notions from arbitrary stimuli can be applied to stimuli that the animal uses in survival.